A. Field of the Invention
The present invention relates to a modular clutch mechanism, and in particular to a modular clutch mechanism in which a flywheel, a clutch cover assembly and a clutch disk assembly form a single module that is installed and replaced as a single unit on a crankshaft of an engine.
B. Description of the Background Art
A clutch device generally includes a flywheel fixed to a crank shaft of an engine, a clutch cover assembly fixed to the flywheel and a clutch disk assembly arranged between the flywheel and the clutch cover assembly. Typically, the flywheel, clutch disk assembly and the clutch cover assembly are separate elements, each being repairable and replaceable irrespective of the other elements.
In prior art clutch devices, the flywheel is bolted to the crankshaft of the engine. The clutch cover assembly is bolted to the flywheel and the clutch disk assembly is sandwiched between the flywheel and the clutch cover assembly. Replacement of any one element may be achieved by removing the bolts on the clutch cover assembly, removing the clutch cover assembly and the clutch disk assembly and replacing either as necessary. The flywheel may then also be serviced or replaced as necessary.
A problem with the above prior art configuration is that the components, the flywheel, clutch cover and clutch disk assemblies are generally expensive to manufacture and are sometimes costly to service. Typically, both the clutch cover and clutch disk assemblies are replaced together even if only one of the two components is worn or damaged. As well, the flywheel is typically resurfaced upon replacement of the clutch disk and clutch cover assemblies. Therefore, all three components are renewed even if only one of the components is worn or damaged.
Recently, modular clutches have been introduced where the flywheel, clutch cover assembly and clutch disk assembly are assembled in advance to form a single module. Such a modular clutch is fixed to the crank shaft of the engine as a single unit. For example, a flexible plate is fixed in advance to the end of the crankshaft of the engine. An outer peripheral portion of the flexible plate is bolted to an outer peripheral portion of the flywheel. In this case, bolts are inserted from the engine side.
In the conventional modular clutch described above, the clutch cover and the flywheel are fixed together by welding, or the like without using bolts. Elimination of bolts allows reduction in weight and cost. In this semi-permanently fixing manner using caulking, welding or the like, the modular clutch must be entirely exchanged when a friction facing of the clutch disk assembly is worn to the limit. In the prior art modular clutch it is possible that the clutch disk assembly may become worn to its limit while the flywheel and clutch cover assembly are still usable. It is not possible to replace the clutch disk assembly easily using the modular construction described above. Therefore it is desirable to insure that the clutch disk assembly has as long a usable life as possible.